Many modern building codes require the use of barriers in construction to protect the building from air and water penetration. For example, building codes in eastern Canada and the northeastern United States now require air barriers to be used in all construction. Moreover, the existing International Building Code/International Residential Code (IBC/IRC) requires the use of a water-resistive air barrier for all new construction. Water-resistive air barriers may be formed from a variety of materials and structures and applied to the surface of construction sheathing materials (e.g., gypsum panels, oriented strand board (OSB) panels).
Traditionally, three types of water-resistive air barriers may be used to meet building codes. First, fabric type membranes, or “wraps,” may be used to cover the surface of building sheathing panels. However, these fabric wraps are typically unable to withstand wind conditions, suffer from drooping, and are difficult to install at heights. Moreover, the standard method of attaching such fabric membranes to sheathing panels is stapling, which compromises the effectiveness of the membrane as an air or water barrier.
Second, a liquid coating water-resistive air barrier membrane may be applied to sheathing panels. However, these liquid coatings must be applied in the field by qualified contractors, which is time intensive and costly. Moreover, although liquid coatings serve as an effective water barrier, they provide low water vapor permeance, which affects the wall's ability to dry should it get wet during service (e.g., around window penetrations, flashing).
Third, self-adhered, or “peel and stick,” water-resistive air barrier membranes may be applied to sheathing panels. However, these self-adhered membranes are generally not permeable and therefore are not an option in many projects, because the architect or engineer must account for this impermeability in designing the building, to prevent the potential for moisture being trapped inside the wall cavity. Furthermore, self-adhered membranes require the sheathing panels to be dry and often primed prior to application, which significantly slows down the construction process.
Accordingly, it would be desirable to provide improved external sheathing panels and building sheathing systems having water-resistive and air-barrier properties, as well as methods of making such panels.